Rapid elbow movements in patients with torsion dystonia.

Abstract

SUMMARY Rapid, selfpaced and selfterminated elbow flexion movements were studied in a group of 10 patients with dystonia affecting the arms. The movements were slower and for small amplitude movements, more variable than those recorded in normal subjects. The duration of the first agonist burst was prolonged, even when compared with normal subjects deliberately moving slowly. Cocontraction of agonist and antagonist muscles during ballistic movements was common and may contribute to the bradykinesia. These findings are compared with similar studies of other diseases of the motor system. Unlike many other conditions which also reduce the speed of ballistic voluntary movements, the patients with dystonia in the present study showed a normal symmetry of acceleration and deceleration times. One interpretation of this finding is that aspects of the basic motor programmes are relatively preserved in this condition and account for the surprising retention of motor skills shown by some patients with dystonia.

Rate of force production and relaxation is impaired in patients with focal hand dystonia

“…Previous work has identified that dystonic patients are slow when performing voluntary movements [5][6][7][8][9][10]. We have extended this finding to include slowness in isometric force production at the wrist (a clinically involved joint) and the elbow (a joint that did not present with overt clinical symptoms of dystonia).…”

“…For example, patients with writer's cramp have been shown to have an average strength deficit of approximately 20% at the wrist and elbow joints of the clinically involved arm compared to healthy subjects [4]. Dystonic patients have also been shown to be slow at the wrist [5] and elbow joints [6] during single degree of freedom movement and during whole arm movement [7][8][9][10]. These deficits have been shown to be associated with decreased muscle activity and could not be explained by co-contraction of antagonist muscles [4,5].…”

“…Based on previous studies, which examined slowness of movement in patients with dystonia when movements are initiated from a resting state [5][6][7]9,10], we expected that hypothesis one would be supported and that patients would be slower than controls turning on force quickly from rest. It is not known however if this impairment remains or is exacerbated when the requirement for increased force output is superimposed on pre-activated muscle.…”

Movement cueing and motor execution in patients with dystonia: A kinematic study

“…The velocity profiles show accelerative and decelerative phases of similar duration indicating that motor programs governing the execution of rapid elbow movements are preserved in dystonia. 3 Motor performance abnormalities have also been reported during complex, horizontal planar and reaching movements. In a study of self-initiated sequential planar movements, Agostino et al 4 found that dystonic patients were slower than control subjects in completing individual movements and took longer than control subjects to switch from one submovement to the next, but did not show progressive slowing with sequence completion.…”

A kinesthetic motor imagery study in patients with writer' cramp

“…The main clinical abnormalities in WC are present during the execution of hand movements, when the dystonic contractions would be produced by an improper functioning of a sensorimotor link which could lead to abnormalities in the control of the movement 17 . Slowness for writing seems to be mainly related to the clumsiness for the execution of movements due to the abnormal muscular contractions [18][19][20][21][22][23] . However, during KMI, the motor pathways are only partially activated and probably could not account for the abnormalities that we observed.…”